Slider with extended three-dimensional air-bearing surface

ABSTRACT

Disclosed herein is a hard disk drive slider having an extended three-dimensional air-bearing surface (ABS). The slider has an ABS and a back surface opposite the ABS, where at least a portion of the back surface defines a plane (i.e., if the back surface is substantially flat, the back surface itself defines the plane). Defined herein is an ABS function, which describes the characteristics of a portion of the ABS in a two-dimensional plane made by taking a cross-section of the slider perpendicular to the plane defined by the at least a portion of the back surface. The cross-section of the slider taken perpendicular to the plane has an ABS function that is a multi-valued function, which is defined herein as a relation for which, for at least one possible input value along the selected axis in the plane, the relation evaluates to two or more distinct nonzero values.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and hereby incorporates byreference the contents of, U.S. provisional patent application No.62/275,857, filed Jan. 7, 2016, entitled “SLIDERS WITH EXTENDEDTHREE-DIMENSIONAL AIR-BEARING SURFACES, AND METHODS FOR FABRICATING SUCHSLIDERS”, having inventors Weidong Huang and Akiko Tadamasa.

This application is being filed on the same day as, and herebyincorporates by reference the contents of, the related U.S. applicationSer. No. 15/164,817, entitled “FABRICATION PROCESS FOR SLIDER WITHEXTENDED THREE-DIMENSIONAL AIR-BEARING SURFACE”, having inventor WeidongHuang, and Ser. No. 15/164,822, entitled “SLIDER WITH TUNNEL FEATURE”,having inventors Weidong Huang and Akiko Tadamasa.

BACKGROUND

Magnetic storage systems, such as hard disk drives, are used to storelarge amounts of information. A magnetic head in a magnetic storagesystem typically includes a read/write transducer for retrieving andstoring magnetically encoded information on a magnetic recording medium,such as a disk. A suspended slider supports the magnetic head. Theslider provides mechanical support for the magnetic head and theelectrical connections between the magnetic head and the rest of themagnetic storage system.

During operation, the slider floats a small distance above the magneticrecording medium (i.e., the hard disk), which rotates at high speeds.Components of a disk drive move the slider and, therefore, the magnetichead to a desired radial position over the surface of the rotating disk,and the magnetic head reads or writes information. The slider rides on acushion or bearing of air created above the surface of the disk as thedisk rotates at its operating speed. The slider has an air-bearingsurface (ABS) that faces the disk. The ABS is designed to generate anair-bearing force that counteracts a preload bias that pushes the slidertoward the disk. The ABS causes the slider to fly above and out ofcontact with the disk.

Conventional slider fabrication techniques place limitations on thedesign of the slider ABS. There is, however, an ongoing need for sliderdesigns that improve performance of magnetic storage systems.

SUMMARY

Disclosed herein are novel slider designs that improve the performanceof magnetic storage systems and hard disk drives incorporating suchnovel sliders. In some embodiments, a slider comprises an air-bearingsurface (ABS) and a back surface opposite the ABS, where at least aportion of the back surface defines a plane, and an ABS function of across-section of the slider taken perpendicular to the plane is amulti-valued function. In some embodiments, the back surface issubstantially flat, and the plane coincides with the back surface. Insome embodiments, at least a portion of the ABS is substantiallyparallel to the plane.

In some embodiments, the slider further comprises a leading-edgesurface, wherein at least a portion of the leading-edge surface issubstantially perpendicular to the plane, and wherein the cross-sectionis substantially perpendicular or parallel to the at least a portion ofthe leading-edge surface.

In some embodiments, the slider further comprises a trailing-edgesurface, wherein at least a portion of the trailing-edge surface issubstantially perpendicular to the plane, and wherein the cross-sectionis substantially perpendicular or parallel to the at least a portion ofthe trailing-edge surface.

In some embodiments, the slider further comprises an inner-radiussurface, wherein at least a portion of the inner-radius surface issubstantially perpendicular to the plane, and wherein the cross-sectionis substantially perpendicular or parallel to the at least a portion ofthe inner-radius surface.

In some embodiments, the slider further comprises an outer-radiussurface, wherein at least a portion of the outer-radius surface issubstantially perpendicular to the plane, and wherein the cross-sectionis substantially perpendicular or parallel to the at least a portion ofthe outer-radius surface.

In some embodiments, the cross-section is oriented along an axis in theplane, and the multi-valued function has at least two distinct valuesfor at least one input value along the axis. In some embodiments, thecross-section is oriented along an axis in the plane, and themulti-valued function has exactly two distinct values for at least oneinput value along the axis.

In some embodiments, the cross-section intersects a feature comprising aprotrusion from an inner-radius surface or an outer-radius surface ofthe slider. In some such embodiments, the protrusion has a wing shape.

In some embodiments, the slider further comprises a head for readingfrom and writing to a disk.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure herein is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements and in which:

FIG. 1 illustrates several components of an exemplary hard disk drive inaccordance with some embodiments.

FIG. 2A illustrates an exemplary slider having a mask applied in aprior-art fabrication process.

FIG. 2B illustrates the exemplary slider of FIG. 2A after the removal ofportions not protected by the mask.

FIG. 2C illustrates the back surface of the exemplary slider of FIG. 2B.

FIG. 2D illustrates a cross-section of the exemplary slider illustratedin FIGS. 2B and 2C.

FIG. 2E illustrates a cross-section of an exemplary slider created byremoving additional material from the slider shown in FIGS. 2B and 2C.

FIGS. 3A through 3C illustrate different views of an exemplary sliderhaving an air-bearing surface with four levels.

FIG. 4A illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 4B illustrates a feature of a slider.

FIG. 4C illustrates a feature of a slider.

FIG. 5A illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 5B illustrates a feature of a slider.

FIG. 5C illustrates a feature of a slider.

FIG. 6 illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 7 illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 8 illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 9 illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 10 illustrates a cross-section of an exemplary slider in accordancewith some embodiments.

FIG. 11 illustrates an exemplary slider having features in accordancewith some embodiments.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present disclosure and is not meant to limitthe inventive concepts claimed herein. Furthermore, particularembodiments described herein may be used in combination with otherdescribed embodiments in various possible combinations and permutations.

FIG. 1 illustrates several components of an exemplary hard disk drive500 in accordance with some embodiments. The magnetic hard disk drive500 includes a spindle 515 that supports and rotates a magnetic disk520. The spindle 515 is rotated by a spindle motor (not shown) that iscontrolled by a motor controller (not shown) that may be implemented inelectronics of the hard disk drive 500. A slider 525, which is supportedby a suspension and actuator arm 530, has a combined read and writemagnetic head 540. The head 540 may include only one read sensor, or itmay include multiple read sensors. The read sensors in the head 540 mayinclude, for example, one or more giant magnetoresistance (GMR) sensors,tunneling magnetoresistance (TMR) sensors, or another type ofmagnetoresistive sensor. An actuator 535 rotatably positions thesuspension and actuator arm 530 over the magnetic disk 520. Thecomponents of the hard disk drive 500 may be mounted on a housing 545.It is to be understood that although FIG. 1 illustrates a single disk520, a single slider 525, a single head 540, and a single suspension andactuator arm 530, hard disk drive 500 may include a plurality (i.e.,more than one) of disks 520, sliders 525, heads 540, and suspension andactuator arms 530.

In operation, the actuator 535 moves the suspension and actuator arm 530to position the slider 525 so that the magnetic head 540 is in atransducing relationship with the surface of the magnetic disk 520. Whenthe spindle motor rotates the disk 520, the slider 525 is supported on athin cushion of air known as the air bearing that exists between thesurface of the disk 520 and an air-bearing surface of the slider 525.The head 540 may be used to write information to multiple tracks on thesurface of the disk 520 and to read previously-recorded information fromthe tracks on the surface of the disk 520. Processing circuitry 510provides to the head 540 signals representing information to be writtento the disk 520 and receives from the head 540 signals representinginformation read from the disk 520. The processing circuitry 510 alsoprovides signals to the spindle motor to rotate the magnetic disk 520,and to the actuator 535 to move the slider 525 to various tracks.

To read information from the magnetic disk 520, the slider 525 passesover a region of the disk 520, and the head 540 detects changes inresistance due to magnetic field variations recorded on the disk 520,which represent the recorded bits.

The slider 525 has a gas-bearing surface that faces the surface of thedisk 520 and counteracts a preload bias that pushes the slider towardthe disk 520. For convenience, in this document the gas-bearing surfaceis referred to as the air-bearing surface (ABS) and the gas is generallyreferred to as “air,” although it is to be understood that the gas usedin a hard disk drive 500 may be a gas other than air (e.g., the gas maybe helium). For simplicity, throughout this disclosure, the surface ofthe slider 525 that faces or that will eventually face the disk 520 isreferred to as the ABS.

As the disk 520 rotates, the disk 520 drags air under the slider 525 andalong the ABS in a direction approximately parallel to the tangentialvelocity of the disk 520. As the air passes under the ABS, aircompression along the air flow path causes the air pressure between thedisk 520 and the ABS to increase, which creates a hydrodynamic liftingforce that counteracts the tendency of the suspension and actuator arm530 to push the slider 525 toward the disk 520. The slider 525 thusflies above the disk 520 but in close proximity to the surface of thedisk 520. To obtain good performance, it is desirable for the slider 525to maintain a substantially constant flying height above the surface ofthe disk 520. The degree of stability of the fly-height of the sliderinfluences the performance of the magnetic head 540. The design of theslider 525 ABS has an impact on the flying characteristics of the slider525 and therefore the performance of the magnetic head 540.

A conventional slider 525 ABS may include a pair of raised side railsthat face the disk 520 surface. The raised side rails may be separatedby an etched cavity and have tapered or stepped leading edges.Additional stepped surfaces may also be formed at various otherlocations on the slider 525 ABS.

Conventionally, the slider 525 is fabricated from a wafer using aphotolithography process having two steps: (a) covering a portion of asurface of the wafer, and (b) removing substrate material from theexposed (i.e., not covered) surface of the wafer. Step (a) may beaccomplished, for example, using a binary mask having hard edges tocreate a well-defined pattern in a photoresist layer that is applied tothe wafer surface. Step (b) may be accomplished, for example, bylapping, etching, or milling (e.g., using an ion beam) to transfer thephotoresist pattern to the wafer surface. The surface of the slider 525to which the covering is applied and from which material is removed isthe surface that will eventually face the disk 520 when the slider 525is used in a disk drive 500, i.e., the ABS. The steps (a) and (b) may berepeated multiple times to create different slider features.

FIGS. 2A through 2C illustrate an exemplary slider 525A being fabricatedusing a prior-art fabrication process having two steps as describedabove. FIGS. 2A, 2B, and 2C show a three-dimensional wafer 120 orientedaccording to the three-dimensional axes shown in FIGS. 2A through 2C,which use rectangular coordinates in directions labeled as x, y, and z.It is to be understood that the labeling of the three axes as x, y, andz is arbitrary. Furthermore, it is to be understood that the use of arectangular coordinate system is convenient because the wafer 120initially has a cuboid shape, but other coordinate systems (e.g., polar,cylindrical, spherical) could be used instead, but might not be asconvenient if the wafer 120 has a cuboid shape. Moreover, the x-, y-,and z-axes are oriented parallel and perpendicular to the surfaces ofthe wafer 120 shown in FIG. 2A for convenience and to simplify theexplanations herein.

As illustrated in FIG. 2A, before fabrication begins, the wafer 120 hasa substantially flat initial surface 145 that lies in an x-y plane. Theinitial surface 145 is the surface of the wafer 120 from which materialis removed to form an ABS having features such as those describedpreviously (e.g., side rails, edges, stepped surfaces, etc.). The wafer120 also has a substantially flat back surface 125, shown in FIG. 2C,which also lies in an x-y plane. Because material is not removed fromthe back surface 125 during fabrication, the back surface 125 remainssubstantially flat in the finished slider 525A.

To create an exemplary slider 525A from the wafer 120, a mask 130, shownin FIG. 2A, is applied to the initial surface 145 to protect the regionsof the initial surface 145 under the mask 130. Material is then removedfrom the portion of the wafer 120 that is not protected by the mask 130.There are many ways to accomplish the removal, such as, for example, byetching the initial surface 145 from a direction perpendicular to theinitial surface 145 (i.e., from above the initial surface 145 asillustrated in FIG. 2A) or by using an ion mill with ions aimed at theinitial surface 145 in the z-direction. As a result of the removal ofmaterial from the wafer 120, only the portion of the initial surface 145protected by the mask 130 remains intact.

FIG. 2B shows the slider 525A after regions of the wafer 120 notprotected by the mask 130 have been removed from the z-direction (e.g.,by directing an ion beam at the initial surface 145 from above the wafer120). As shown in FIG. 2B, the portion of the wafer 120 that was underthe mask 130 remains intact, whereas material from the wafer 120 thatwas not under the mask 130 has been removed. Assuming for the sake ofexample that the slider 525A is now complete, the ABS 140 is thethree-dimensional surface that includes the portion of the initialsurface 145 previously protected by the mask 130 (i.e., the portion ofthe initial surface 145 that remains after removal of material from thewafer 120) and the newly-created surface in the wafer 120, which isrecessed from the plane that contained the initial surface 145. Thus,the ABS 140 of FIG. 2B has two levels, 155A and 155B.

As shown in FIG. 2B, the slider 525A has transitions in the z-directionbetween the levels 155A (i.e., regions of the wafer 120 formerly coveredby the mask 130) and 155B (i.e., the now-exposed regions of the wafer120 from which material was removed). For example, FIG. 2B labels twoz-direction transitions 150A and 150B, although there are, of course,many other z-direction transitions shown.

FIG. 2D shows a cross-section 160A of the exemplary slider 525Aillustrated in FIGS. 2B and 2C. The cross-section 160A is taken parallelto the z-axis and perpendicular to the back surface 125 (i.e., thecross-section is made vertically, perpendicular to the x-y plane basedon the orientation of the axes in FIG. 2B) along the dashed line 170shown on the level 155A of the slider 525A illustrated in FIG. 2B. Forease of explanation, as shown in FIG. 2D, the cross-section 160A hasbeen taken in an x-z plane defined by the axes illustrated in FIGS. 2Aand 2B. Therefore, the cross-section 160A illustrates how the ABS 140varies along the z-axis as a function of the value along the x-axis atwhatever fixed value of y is represented by the line 170 in FIG. 2B.

As used herein, the term “single-valued function” means a relation f(x)for which, for all possible values of x, f(x) has exactly one value or adiscontinuity.

As used herein, the term “multi-valued function” means a relation f(x)for which, for at least one possible value of x, f(x) has two or moredistinct nonzero values. For purposes of the definition of multi-valuedfunction herein, a discontinuity does not have two or more distinctnonzero values.

The terms “single-valued function” and “multi-valued function” as usedherein are mutually exclusive. A single-valued function cannot be amulti-valued function, and a multi-valued function cannot be asingle-valued function, even if, in some range of x values, themulti-valued function has all of the properties of a single-valuedfunction. In other words, as used herein, a function can be either asingle-valued function or a multi-valued function, but not both.

As will be appreciated by a person having ordinary skill in the art, asused herein, the terms “function,” “single-valued function,” and“multi-valued function” do not necessarily comport with those terms asthey may be used in mathematics. For example, in mathematics the terms“function” and “single-valued function” typically mean a relation inwhich for each input there is exactly one output. Here, a single-valuedfunction may also include a discontinuity, meaning that for a selectedvalue of x at which a discontinuity occurs, the single-valued functionf(x) evaluates to many values in a range defined by the discontinuity.

The term “ABS function” is used herein to describe the characteristicsof a portion of the ABS 140 in a two-dimensional plane made by taking across-section of the slider 525 parallel to the z-axis and perpendicularto the x-y plane (i.e., the plane defined by the back surface 125,assuming the back surface 125 is substantially flat). Using theorientation of axes presented herein, i.e., with the initial surface 145and back surface 125 lying in parallel x-y planes, the ABS functiondescribes how the ABS 140 varies in the z-direction along a selectedaxis in an x-y plane. The ABS function does not include any portion ofthe back surface 125.

Using the definitions provided above, an ABS function in which, for allpossible input values along the selected axis in the x-y plane, the ABSfunction has exactly one value or a discontinuity is a single-valuedfunction. In other words, the ABS function is a single-valued functionif, for all possible input values along the selected axis in the x-yplane, the ABS function has exactly one value or a discontinuity. Incontrast, an ABS function having at least one input value along theselected axis in the x-y plane for which the ABS function has two ormore distinct nonzero z-values is a multi-valued function. Thus, the ABSfunction is a multi-valued function if, for at least one input valuealong the selected axis in the x-y plane, the ABS function has two ormore distinct nonzero z-values. It is to be appreciated that an ABSfunction need not be continuous, as some of the exemplary new sliderembodiments herein will illustrate.

FIG. 2D shows the ABS function 180A resulting from the exemplarycross-section 160A. For clarity, the ABS function 180A is shown in bold.As is evident from FIG. 2D, the ABS function 180A is a piecewise linearfunction. As explained previously, for ease of explanation, thecross-section 160A is taken parallel to the x-axis at a selected valueof y, and therefore the axis in the x-y plane is simply an x-axis. Asshown by the vertical dashed line 165 in FIG. 2D, which may bepositioned anywhere along the x-axis, for any selected value of x alongthe cross-section 160A, the ABS function 180A has either exactly onez-value, or there is a vertical transition, i.e., a discontinuity, atthat value of x. For example, as shown in FIG. 2D, when the value of xis X1, the ABS function 180A has exactly one nonzero z-value, Z1. Whenthe value of x is X2, the ABS function 180A has a discontinuity andevaluates to all values between Z1 and Z4. Therefore, the ABS function180A is a single-valued function.

Although FIG. 2D shows only one exemplary cross-section of the slider525A illustrated in FIG. 2B, as will be understood by those havingordinary skill in the art after reading and understanding thedisclosures herein, the ABS function 180 resulting from anycross-section 160 of the slider 525A illustrated in FIG. 2B madeparallel to the z-axis and perpendicular to an x-y plane will be asingle-valued function. This ABS function 180 will be a single-valuedfunction regardless of the orientation of the cross-section 160 withrespect to the x- and y-axes (i.e., regardless of which axis in the x-yplane is selected); as long as the cross-section 160 is made parallel tothe z-axis (i.e., perpendicular to the x-y plane), the resulting ABSfunction 180 will be a single-valued function.

It is to be appreciated that the value of y that coincides with the line170 in FIG. 2B is arbitrary. The line 170 could be moved to anothervalue of y along the y-axis, and the resulting cross-section 160 wouldhave similar characteristics to the cross-section 160A shown in FIG. 2D.Specifically, the resulting cross-section 160 would have an ABS function180 that is a single-valued function. Furthermore, the line 170 could beoriented parallel to the y-axis instead of parallel to the x-axis,thereby defining a cross-section 160 in the y-z plane instead of in thex-z plane as shown in FIG. 2C. In this case, too, the resultingcross-section 160 would have similar characteristics to thecross-section 160A shown in FIG. 2D; in other words, that cross-section160 would also have an ABS function 180 that is a single-valuedfunction. It is also to be appreciated that, as shown in FIG. 2B, theline 170 is parallel to the y-axis, and therefore represents a singlevalue of y, only for ease of explanation and presentation. Across-section 160 taken parallel to the z-axis and perpendicular to anyarbitrary axis in the x-y plane would have similar characteristics tothe cross-section 160A shown in FIG. 2D (i.e., would have an ABSfunction 180 that is a single-valued function) but could be morecomplicated to describe using the axes shown in FIGS. 2A through 2Cbecause both the value of x and the value of y could vary along thecross-section 160.

As explained above, FIG. 2B illustrates an exemplary slider 525A createdusing only one mask 130, but additional masks may be applied to theslider 525A shown in FIG. 2B to create additional features or contours.For example, a different mask may be applied to the slider 525A of FIG.2B to cover not only the region formerly covered by the mask 130, butalso additional exposed areas of the wafer 120, and additional materialmay subsequently be removed from the wafer 120. Alternatively, a maskthat does not entirely cover the region covered by the mask 130 may beapplied, and material from the portion of the wafer 120 formerlyprotected by the mask 130 may then be removed along with material fromelsewhere on the wafer 120. After the removal of material unprotected byeach mask, yet another mask may be applied and yet more materialremoved, and so on.

FIG. 2E illustrates a cross-section 160B of an exemplary slider (notshown) created by removing additional material from the wafer 120 shownin FIG. 2B. Like the cross-section 160A of FIG. 2D, the cross-section160B is taken in the z-direction, parallel to the z-axis andperpendicular to an x-y plane (e.g., the x-y plane that coincides withthe back surface 125) along a selected axis in the x-y plane. For easeof explanation, the cross-section 160B has been taken parallel to thex-axis (and perpendicular to the y-axis) and therefore, like thecross-section 160A of FIG. 2D, lies in an x-z plane defined by the axesillustrated in FIGS. 2A through 2C. Therefore, the cross-section 160Billustrates how the ABS function 180B varies (in the direction of thez-axis) as a function of the value along the x-axis at a selected valueof y. Again, for clarity, the ABS function 180B is shown in bold. Asshown by FIG. 2E, although the ABS function 180B has more contours andtransitions than the ABS function 180A, the ABS function 180B is still asingle-valued function because for any selected value of x at which theline 165 may be located, the ABS function 180B has exactly one nonzerovalue or a discontinuity.

FIGS. 3A through 3C illustrate a more complicated exemplary slider 525Bcreated by a prior-art process in which the steps of applying a mask andremoving material from unprotected regions of the wafer 120 have beenexecuted three times to create an ABS 140 having four levels. The slider525B has six surfaces: the back surface 125 (shown in FIG. 3C), aleading-edge surface 121 (shown in FIGS. 3A and 3C), a trailing-edgesurface 122 (shown in FIG. 3B), an inner-radius surface 123 (shown inFIGS. 3A and 3C), an outer-radius surface 124 (shown in FIG. 3B), and anABS 140 (shown in FIGS. 3A and 3B). In the exemplary slider 525B shownin FIGS. 3A through 3C, the leading-edge surface 121, trailing edgesurface 122, inner-radius surface 123, and outer-radius surfaces 124 aresubstantially perpendicular to the back surface 125. The leading-edgesurface 121 and trailing-edge surface 122 are substantially parallel toeach other, and the inner-radius surface 123 and outer-radius surface124 are substantially parallel to each other. The leading-edge surface121 and trailing-edge surface 122 are both substantially perpendicularto both of the inner-radius surface 123 and the outer-radius surface124. In some embodiments, the leading-edge surface 121, trailing-edgesurface 122, inner-radius surface 123, and outer-radius surface 124 maybe substantially perpendicular to at least a portion of the ABS 140.

A first level 142 of the ABS 140 is the level of the ABS 140 that willbe closest to the disk 520 when the slider 525B is incorporated into adisk drive 500. A second level 144 is the level that will be thenext-closest to the disk 520. A fourth level 148 is the level that willbe furthest from the disk 520, and a third level 146 is the level thatwill be next-furthest from the disk 520.

The slider 525B shown in FIGS. 3A through 3C may be fabricated asfollows. First, a mask having the shape of the first level 142 isapplied to a cuboid wafer 120, as previously described in the discussionof FIGS. 2A through 2C. Material down to the surface of the second level144 is then removed from the wafer 120, creating a two-level ABS 140.Next, a mask having the shape that is the union of the shape of thefirst level 142 and the second level 144 is applied to the ABS 140, andmaterial not protected by the mask is removed from the wafer 120,creating a three-level ABS 140 that includes the third level 146.Finally, a mask having the shape that is the union of the shapes of thefirst level 142, the second level 144, and the third level 146 isapplied to the ABS 140, and material not protected by the mask isremoved from the wafer 120 to create the fourth level 148, as shown inFIGS. 3A and 3B.

Although the process of protecting a portion of the wafer 120 andremoving material from the unprotected portion of the wafer 120 may berepeated multiple times with masks having different sizes and shapes tocreate a relatively complex ABS 140, such as the exemplary ABS 140 shownin FIGS. 3A through 3C, prior-art fabrication methods only allow for theremoval or preservation of wafer 120 material. As a result, when aslider 525 is fabricated using prior-art techniques, in which materialis removed from a particular direction, along a particular axis (assumedherein to be the z-axis using the orientation of axes shown in FIGS. 2Athrough 2C) perpendicular to the plane in which the back surface 125lies (assumed herein to be the x-y plane), the ABS function 180 for anycross-section 160 taken perpendicular to the plane of the back surface125 is a single-valued function. One can verify by inspection of FIGS.3A through 3C that even more sophisticated sliders having multiplelevels and more complex shapes have ABS functions 180 that aresingle-valued functions. Any cross-section 160 of the exemplary slider525B illustrated in FIGS. 3A through 3C taken perpendicular to the x-yplane of the back surface 125 will result in an ABS function 180 that isa single-valued function.

Because prior-art slider fabrication processes only allow the removal ofmaterial from one direction, previously-existing slider fabricationmethods impose significant limitations on the design of sliders 525. Asa consequence, existing slider designs can have several drawbacks,including a tendency to collect lubricant, which affects theaerodynamics of a slider 525. Lubricant pickup occurs when lubricantcoated on the surface of the disk 520 collects on the ABS 140. Oncecollected on the ABS 140, the lubricant tends to interfere with thefly-height of the slider 525, causing the slider 525 to have a tendencyto fly at an inconsistent height, which results in degraded magneticinterfacing between the slider 525 and the disk 520.

Another problem with existing slider designs is that, because existingslider designs are constrained by prior-art fabrication processes, theyimpose limits on the types of features sliders 525 may have. There aremany features that simply cannot be created economically—or, in somecases, at all—using prior-art fabrication techniques. These limitationsaffect designers' ability to create sliders 525 having more optimalaerodynamic and other properties.

A related application, identified above and incorporated by referenceherein, discloses novel slider fabrication processes that improve uponprior-art processes by enabling additive fabrication, i.e., the additionof material to the wafer 120 instead of simply the preservation orremoval of wafer 120 material. These processes enable the fabrication ofslider features that were previously impossible, impractical, tooexpensive, or too time-consuming to create.

Disclosed herein are slider 525 designs with novel ABS 140 features thatprovide numerous advantages, such as, for example, low vibration duringself-servo write and operation, low spacing sensitivity tointermolecular force, balanced head transfer between the reader andwriter, fast takeoff from thermal fly-height control (TFC) touchdown,increased robustness to particle and lubrication interference, and lowspacing sensitivity to flatness change. Unlike prior-art sliders, thesenew sliders 525 have at least one ABS function 180 that is amulti-valued function. In other words, there is at least onecross-section 160 taken perpendicular to the plane in which thesubstantially flat back surface 125 of the slider 525 lies (i.e., thex-y plane with the axes oriented as described for FIGS. 2A through 2C;in other words, the cross-section 160 is taken parallel to the z-axisshown in FIGS. 2A through 2C) for which the ABS function 180 is amulti-valued function.

FIG. 4A illustrates an ABS function 180C of a slider cross-section 160Cin accordance with some embodiments assuming axes oriented as shown inFIGS. 2A-2C and 3A-3C. For clarity, the ABS function 180C is shown inbold. For convenience, the cross-section 160C has been taken parallel tothe x-axis at a particular value along the y-axis and therefore lies inan x-z plane. Thus, the cross-section 160C illustrates how the ABSfunction 180C varies in the direction of the z-axis as a function of thevalue along the x-axis at a selected value of y. In embodiments in whichthe leading-edge surface 121 and the trailing-edge surface 122 aresubstantially parallel, the cross-section 160C is likewise substantiallyparallel to the leading-edge surface 121 and the trailing-edge surface122. Likewise, in embodiments in which the inner-radius surface 123 andthe outer-radius surface 124 are substantially parallel to each otherand substantially perpendicular to the leading-edge surface 121 and thetrailing-edge surface 122, the cross-section 160C is substantiallyperpendicular to the inner-radius surface 123 and the outer-radiussurface 124.

The cross-section 160C intersects a feature 190. The feature 190 may be,for example, a rectangular channel or tunnel that extends for somedistance in the y-direction of the slider 525, as illustrated in FIG.4B. FIG. 4B shows an exemplary embodiment of the feature 190 from they-z plane assuming that the selected value of y at which thecross-section 160C of FIG. 4A was taken is Y1, shown in FIG. 4B.Alternatively, as another example, the feature 190 may be a recessedarea of the slider 525 that extends for some distance along they-direction of the slider 525. FIG. 4C illustrates an exemplary recessedarea viewed in the y-z plane. FIG. 4C also shows the value Y1 at whichthe cross-section 160C of FIG. 4A was assumed to have been taken. It isto be understood that although FIG. 4C illustrates a rectangular openingfor the recessed area, the opening may have any arbitrary shape thatcorresponds to the feature 190 of the ABS function 180C shown in FIG.4A. It is to be appreciated that there are myriad slider characteristicsin a y-z plane (e.g., uniform or non-uniform characteristics) that wouldresult in the exemplary feature 190 of FIG. 4A in an x-z plane, and theexamples shown in FIGS. 4B and 4C are not intended to be limiting.

Referring again to FIG. 4A, the exemplary ABS function 180C is amulti-valued function because there is at least one value of x for whichthe ABS function 180C has at least two distinct nonzero values.Specifically, the ABS function 180C has at least two distinct nonzerovalues at the locations along the x-axis intersecting the feature 190.For example, at the value of x corresponding to the location of the line165, the ABS function 180C has three distinct values: Z2, Z3, and Z4.

As would be appreciated by a person having ordinary skill in the art,the feature 190 would be impossible, impractical, too expensive, or tootime-consuming to create using prior-art fabrication techniques.

FIG. 5A illustrates an ABS function 180D of a slider cross-section 160Din accordance with some embodiments. Again, for clarity, the ABSfunction 180D is shown in bold. For convenience, the cross-section 160Dhas been taken parallel to the x-axis at a particular value along they-axis and therefore lies in an x-z plane defined by the axesillustrated in FIGS. 2A-2C and 3A-3C. Therefore, the cross-section 160Dillustrates how the ABS function 180D varies in the direction of thez-axis as a function of the value along the x-axis at a selected valueof y. In embodiments in which the leading-edge surface 121 and thetrailing-edge surface 122 are substantially parallel, the cross-section160D is likewise substantially parallel to the leading-edge surface 121and the trailing-edge surface 122. Likewise, in embodiments in which theinner-radius surface 123 and the outer-radius surface 124 aresubstantially parallel to each other and substantially perpendicular tothe leading-edge surface 121 and the trailing-edge surface 122, thecross-section 160D is substantially perpendicular to the inner-radiussurface 123 and the outer-radius surface 124.

The cross-section 160D intersects a feature 192. The feature 192 may be,for example, a non-rectangular (e.g., semi-circular, cylindrical,irregularly-shaped, etc.) channel or tunnel that extends for somedistance along the y-direction of the slider 525, as illustrated in FIG.5B. FIG. 5B shows an exemplary embodiment of the feature 192 from a y-zplane assuming that the selected value of y at which the cross-section160D of FIG. 5A was taken is Y1, shown in FIG. 5B. Alternatively, thefeature 192 may be, for example, a recessed area of the slider 525 thatextends for some distance along the y-direction of the slider 525. Therecessed area may have any arbitrary shape that creates the feature 192of the ABS function 180D shown in FIG. 5A. FIG. 5C illustrates anexemplary recessed area viewed in a y-z plane. FIG. 5C also shows thevalue Y1 at which the cross-section 160C of FIG. 5A was taken. AlthoughFIG. 5C illustrates a slider characteristic having a fairly regularshape, the feature 192 need not be the result of a slider characteristichaving a regular shape. The slider characteristic may have any shapethat results in the feature 192 shown in FIG. 5A. It is to beappreciated that there are myriad slider characteristics in a y-z planethat would result in the exemplary feature 192 of FIG. 5A in an x-zplane, and the examples shown in FIGS. 5B and 5C are not intended to belimiting.

Referring again to FIG. 5A, the exemplary ABS function 180D is amulti-valued function because there is at least one value of x for whichthe ABS function 180D has at least two distinct nonzero values.Specifically, the ABS function 180D has at least two distinct nonzerovalues at the locations along the x-axis intersecting the feature 192.For example, at the value of x corresponding to the location of the line165, the ABS function 180D has three distinct values: Z4, Z5, and Z6.

As would be appreciated by a person having ordinary skill in the art,the feature 192 would be impossible, impractical, too expensive, or tootime-consuming to create using prior-art fabrication techniques.

FIG. 6 illustrates an ABS function 180E of a slider cross-section 160Ein accordance with some embodiments. Again, for clarity, the ABSfunction 180E is shown in bold. For convenience, the cross-section 160Ehas been taken parallel to the x-axis at a particular value along they-axis and therefore lies in an x-z plane defined by the axesillustrated in FIGS. 2A-2C and 3A-3C. Therefore, the cross-section 160Eillustrates how the ABS function 180E varies in the direction of thez-axis as a function of the value along the x-axis at a selected valueof y. In embodiments in which the leading-edge surface 121 and thetrailing-edge surface 122 are substantially parallel, the cross-section160E is likewise substantially parallel to the leading-edge surface 121and the trailing-edge surface 122. Likewise, in embodiments in which theinner-radius surface 123 and the outer-radius surface 124 aresubstantially parallel to each other and substantially perpendicular tothe leading-edge surface 121 and the trailing-edge surface 122, thecross-section 160E is substantially perpendicular to the inner-radiussurface 123 and the outer-radius surface 124.

The cross-section 160E intersects a feature 194, which is a protrusionin the x-direction of the slider 525. For example, the feature 194 maybe a rail, having a uniform or a non-uniform shape, which extends forsome distance in the y-direction of the slider 525, as shown in FIG. 6.Alternatively, the feature 194 may be a bump, a dome, or a protrusionhaving a non-uniform shape. It is to be appreciated that there aremyriad slider characteristics that would result in the exemplary feature194 of FIG. 6 in an x-z plane, and the examples provided herein are notintended to be limiting.

The exemplary ABS function 180E is a multi-valued function because thereis at least one value of x for which the ABS function 180E has at leasttwo distinct nonzero values. Specifically, the ABS function 180E has atleast two distinct nonzero values at the locations along the x-axisintersecting the feature 194. For example, at the value of xcorresponding to the location of the line 165, the ABS function 180E hasthree distinct values: Z1, Z7, and Z8.

As would be appreciated by a person having ordinary skill in the art,the feature 194 would be impossible, impractical, too expensive, or tootime-consuming to create using prior-art fabrication techniques.

FIG. 7 illustrates an ABS function 180F of a slider cross-section 160Fin accordance with some embodiments. Again, for clarity, the ABSfunction 180F is shown in bold. Note that the ABS function 180F isdiscontinuous. For convenience, the cross-section 160F has been takenparallel to the x-axis at a particular value along the y-axis andtherefore lies in an x-z plane defined by the axes illustrated in FIGS.2A-2C and 3A-3C. Therefore, the cross-section 160F illustrates how theABS function 180F varies in the direction of the z-axis as a function ofthe value along the x-axis at a selected value of y. In embodiments inwhich the leading-edge surface 121 and the trailing-edge surface 122 aresubstantially parallel, the cross-section 160F is likewise substantiallyparallel to the leading-edge surface 121 and the trailing-edge surface122. Likewise, in embodiments in which the inner-radius surface 123 andthe outer-radius surface 124 are substantially parallel to each otherand substantially perpendicular to the leading-edge surface 121 and thetrailing-edge surface 122, the cross-section 160F is substantiallyperpendicular to the inner-radius surface 123 and the outer-radiussurface 124.

The cross-section 160F intersects a feature 196, which, in theembodiment illustrated in FIG. 7, is a cavity or tunnel along thex-direction that extends into the slider 525 in the y-direction.Although FIG. 7 illustrates a rectangular cavity or tunnel, the feature196 may have any convenient size and shape. For example, the feature 196may have a uniform or a non-uniform shape that extends, uniformly ornon-uniformly, for some distance parallel to the x- and z-axes of theslider 525 and that extends in some uniform or non-uniform way into theslider 525 in the y-direction (i.e., parallel to the y-axis). As anotherexample, the feature 196 may have a first size and shape at a firstvalue of y (e.g., Y1, not shown) and a second size and shape at a secondvalue of y (e.g., Y2, not shown). In other words, the feature 196 mayhave an irregular shape and/or a non-uniform size that may changedepending on where the cross-section 160F is taken. It is to beappreciated that there are myriad slider characteristics that wouldresult in exemplary features (e.g., uniform or non-uniform cavities ortunnels) similar to the feature 196 of FIG. 7 in an x-z plane, and theexamples provided herein are not intended to be limiting.

The feature 196 is part of the ABS 140, and therefore the ABS function180F includes the feature 196, even though the resultant ABS function180F is discontinuous (i.e., the portion of the ABS function 180Fcorresponding to the feature 196 does not intersect the rest of the ABSfunction 180F). The exemplary ABS function 180F is a multi-valuedfunction because there is at least one value of x for which the ABSfunction 180F has at least two distinct nonzero values. For example, theABS function 180F has at least two distinct nonzero values at thelocations along the x-axis intersecting the feature 196. For example, atthe value of x corresponding to the location of the line 165 shown inFIG. 7, the ABS function 180F has three distinct values: Z4, Z9, andZ10.

As would be appreciated by a person having ordinary skill in the art,the feature 196, and features having characteristics similar to thecharacteristics of feature 196, would be impossible, impractical, tooexpensive, or too time-consuming to create using prior-art fabricationtechniques.

FIG. 8 illustrates an ABS function 180G of a slider cross-section 160Gin accordance with some embodiments. Again, for clarity, the ABSfunction 180G is shown in bold. For convenience, the cross-section 160Ghas been taken parallel to the x-axis at a particular value along they-axis and therefore lies in an x-z plane defined by the axesillustrated in FIGS. 2A-2C and 3A-3C. Therefore, the cross-section 160Gillustrates how the ABS function 180G varies in the direction of thez-axis as a function of the value along the x-axis at a selected valueof y. In embodiments in which the leading-edge surface 121 and thetrailing-edge surface 122 are substantially parallel, the cross-section160G is likewise substantially parallel to the leading-edge surface 121and the trailing-edge surface 122. Likewise, in embodiments in which theinner-radius surface 123 and the outer-radius surface 124 aresubstantially parallel to each other and substantially perpendicular tothe leading-edge surface 121 and the trailing-edge surface 122, thecross-section 160G is substantially perpendicular to the inner-radiussurface 123 and the outer-radius surface 124.

The cross-section 160G intersects a feature 198, which, in theembodiment illustrated in FIG. 8, manifests as a protrusion in the x-and z-directions. Although FIG. 8 illustrates a cylindrical protrusion,the feature 198 may have any convenient shape. For example, the feature198 may have a uniform or a non-uniform shape that extends for somedistance parallel to the x-, y-, and z-axes of the slider 525. It is tobe appreciated that there are myriad slider characteristics that wouldresult in features similar to the feature 198 of FIG. 8 in an x-z plane,and the examples provided herein are not intended to be limiting.

The exemplary ABS function 180G is a multi-valued function because thereis at least one value of x for which the ABS function 180G has at leasttwo distinct nonzero values. For example, the ABS function 180G has atleast two distinct nonzero values at the locations along the x-axisintersecting the feature 198. For example, at the value of xcorresponding to the location of the line 165, the ABS function 180G hasthree distinct values: Z1, Z11, and Z12.

As would be appreciated by a person having ordinary skill in the art,the feature 198, and features having characteristics similar to thecharacteristics of feature 198, would be impossible, impractical, tooexpensive, or too time-consuming to create using prior-art fabricationtechniques.

The ABS functions 180 corresponding to sliders 525 having the exemplaryfeatures 190, 192, 194, 196, and 198 are all multi-valued functionshaving, at most, three values of f(x) for at least one value of x. It isalso possible for a slider 525 to have an ABS function having more thanthree values of f(x) for at least one value of x. FIG. 9 illustratessuch an embodiment of an ABS function 180H having five values for atleast one input value. Again, for clarity, the ABS function 180H isshown in bold. For convenience, the cross-section 160H has been takenparallel to the x-axis at a particular value along the y-axis andtherefore lies in an x-z plane defined by the axes illustrated in FIGS.2A-2C and 3A-3C. Therefore, the cross-section 160H illustrates how theABS function 180H varies in the direction of the z-axis as a function ofthe value along the x-axis at a selected value of y. In embodiments inwhich the leading-edge surface 121 and the trailing-edge surface 122 aresubstantially parallel, the cross-section 160H is likewise substantiallyparallel to the leading-edge surface 121 and the trailing-edge surface122. Likewise, in embodiments in which the inner-radius surface 123 andthe outer-radius surface 124 are substantially parallel to each otherand substantially perpendicular to the leading-edge surface 121 and thetrailing-edge surface 122, the cross-section 160H is substantiallyperpendicular to the inner-radius surface 123 and the outer-radiussurface 124.

The cross-section 160H intersects a feature 191, which, in the exemplaryembodiment illustrated in FIG. 9, results from two “shelves” extendingin the x- and y-directions from a vertical surface (i.e., in thez-direction) of the slider 525. It is to be appreciated that there aremyriad slider characteristics that would result in the exemplary feature191 of FIG. 9 in an x-z plane, and the examples provided herein are notintended to be limiting.

The exemplary ABS function 180H is a multi-valued function because thereis at least one value of x for which the ABS function 180H has at leasttwo distinct nonzero values. For example, the ABS function 180H has atleast two distinct nonzero values at the locations along the x-axisintersecting the feature 191. For example, at the value of xcorresponding to the location of the line 165, the ABS function 180H hasfive distinct values: Z1, Z11, Z12, Z13, and Z14.

It is to be understood that the ABS function 180 may also have more thanfive distinct values. The examples of features and the ABS functions 180corresponding to those features presented herein are not intended to belimiting.

It is also to be understood that the ABS function 180 may have exactlytwo distinct values for certain input values along the selected axis inthe x-y plane. As just one example, the slider 525 may have “wings” or“winglets” protruding from the inner-radius surface 123 and/orouter-radius surface 124. Such features could result in a slider 525having enhanced or different aerodynamic properties than, for example, aslider 525 that has a more cuboid overall shape. FIG. 10 illustrates anABS function 180J of a slider cross-section 160J in accordance with someembodiments. Again, for clarity, the ABS function 180J is shown in bold.For convenience, the cross-section 160J has been taken parallel to thex-axis at a particular value along the y-axis and therefore lies in anx-z plane defined by the axes illustrated in FIGS. 2A-2C and 3A-3C.Therefore, the cross-section 160J illustrates how the ABS function 180Jvaries in the direction of the z-axis as a function of the value alongthe x-axis at a selected value of y. In embodiments in which theleading-edge surface 121 and the trailing-edge surface 122 aresubstantially parallel, the cross-section 160J is likewise substantiallyparallel to the leading-edge surface 121 and the trailing-edge surface122. Likewise, in embodiments in which the inner-radius surface 123 andthe outer-radius surface 124 are substantially parallel to each otherand substantially perpendicular to the leading-edge surface 121 and thetrailing-edge surface 122, the cross-section 160J is substantiallyperpendicular to the inner-radius surface 123 and the outer-radiussurface 124.

The cross-section 160J intersects a feature 199, which, in theembodiment illustrated in FIG. 10, is a wing-shaped protrusion in thex-direction from the inner-radius surface 123. It is to be understoodthat a similar-shaped protrusion could also extend from the outer-radiussurface 124. Although FIG. 10 illustrates a wing-shaped protrusion, thefeature 199 may have any convenient shape. For example, the feature 199may have a uniform or a non-uniform shape that extends for some distanceparallel to the x-axis and y-axis of the slider 525. It is to beappreciated that there are myriad slider characteristics that wouldresult in features similar to the feature 199 of FIG. 10 in an x-zplane, and the examples provided herein are not intended to be limiting.

The exemplary ABS function 180J is a multi-valued function because thereis at least one value of x for which the ABS function 180J has at leasttwo distinct nonzero values. For example, the ABS function 180J has atleast two distinct nonzero values at the locations along the x-axisintersecting the feature 199. For example, at the value of xcorresponding to the location of the line 165, the ABS function 180J hasexactly two distinct values: Z11 and Z12. At some other locations alongthe x-axis intersecting the feature 199, the ABS function 180J hasexactly three distinct values, namely Z1, Z11, and Z12.

As would be appreciated by a person having ordinary skill in the art,regardless of the shapes and characteristics of the features 190, 191,192, 194, 196, 198, and 199, these features would be impossible,impractical, too expensive, or too time-consuming to create usingprior-art fabrication techniques. The features 190, 191, 192, 194, 196,198, and 199, and myriad other features may be created, however, usingthe novel fabrication processes disclosed in the related application,“FABRICATION PROCESS FOR SLIDER WITH EXTENDED THREE-DIMENSIONALAIR-BEARING SURFACE,” which, as stated previously, is incorporated byreference.

FIG. 11 illustrates an exemplary slider 525C having features 200Athrough 200F in accordance with some embodiments. As shown in FIG. 11,each of the features 200A through 200F is a cavity or tunnel similar tothe feature 196 shown in FIG. 7. It is to be appreciated, however, thatthe features 200A through 200F may have nonrectangular and/ornon-uniform shapes (e.g., arbitrary shapes), and they may be protrusionsor cavities, such as shown and discussed in the context of the examplesprovided in FIGS. 4 through 10. As will be understood by a person havingordinary skill in the art in view of the disclosures herein, there aremyriad possible size, shapes, and characteristics of features 200Athrough 200F. The examples provided herein are not intended to belimiting.

One can verify by inspection that the slider 525C of FIG. 11 includesmultiple cross-sections 160 that have ABS functions 180 that aremulti-valued functions. For example, there are multiple cross-sections160 of the slider 525C of FIG. 11 that, when taken perpendicular to thex-y plane defined by the substantially flat back surface 125 (notshown), will result in an ABS function 180 that is a multi-valuedfunction. The lines 205, 210, 215, 220, and 225 identify severalexemplary locations at which a cross-section 160 made perpendicular tothe plane of the back surface 125 (i.e., perpendicular to the x-y planeand parallel to the z-axis shown) will result in an ABS function 180that is a multi-valued function. The lines 205, 210, 215, 220, and 225are shown having arbitrary orientations in the x-y plane. Therefore, thelines 205, 210, 215, 220, and 225 also have arbitrary orientations withrespect to the leading-edge surface 121, trailing-edge surface 122,inner-radius surface 123, and outer-radius surface 124 (not shown inFIG. 11; refer to FIGS. 3A-3C). Of course, a cross-section 160 may beparallel or perpendicular to the leading-edge surface 121, trailing-edgesurface 122, inner-radius surface 123, or outer-radius surface 124, andsuch cross-section 160 may also have an ABS function 180 that is amulti-valued function.

In the foregoing description and in the accompanying drawings, specificterminology has been set forth to provide a thorough understanding ofthe disclosed embodiments. In some instances, the terminology ordrawings may imply specific details that are not required to practicethe invention.

To avoid obscuring the present disclosure unnecessarily, well-knowncomponents (e.g., of a disk drive) are shown in block diagram formand/or are not discussed in detail or, in some cases, at all.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation, including meanings implied fromthe specification and drawings and meanings understood by those skilledin the art and/or as defined in dictionaries, treatises, etc. As setforth explicitly herein, some terms may not comport with their ordinaryor customary meanings.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” do not exclude plural referents unless otherwisespecified. The word “or” is to be interpreted as inclusive unlessotherwise specified. Thus, the phrase “A or B” is to be interpreted asmeaning all of the following: “both A and B,” “A but not B,” and “B butnot A.” Any use of “and/or” herein does not mean that the word “or”alone connotes exclusivity.

To the extent that the terms “include(s),” “having,” “has,” “with,” andvariants thereof are used in the detailed description or the claims,such terms are intended to be inclusive in a manner similar to the term“comprising,” i.e., meaning “including but not limited to.” The terms“exemplary” and “embodiment” are used to express examples, notpreferences or requirements.

The terms “over,” “under,” “between,” and “on” are used herein refer toa relative position of one feature with respect to other features. Forexample, one feature disposed “over” or “under” another feature may bedirectly in contact with the other feature or may have interveningmaterial. Moreover, one feature disposed “between” two features may bedirectly in contact with the two features or may have one or moreintervening features or materials. In contrast, a first feature “on” asecond feature is in contact with that second feature.

The drawings are not necessarily to scale, and the dimensions, shapes,and sizes of the features may differ substantially from how they aredepicted in the drawings. Furthermore, the use, labeling, andorientation of the x-, y-, and z-axes are for convenience and tofacilitate the explanations provided herein.

Moreover, although the exemplary wafers 120 and sliders 525 have cuboidshapes, other wafer 120 and slider 525 shapes may be used withoutdeparting from the spirit and scope of this disclosure.

Although specific embodiments have been disclosed, it will be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the disclosure. Forexample, features or aspects of any of the embodiments may be applied,at least where practicable, in combination with any other of theembodiments or in place of counterpart features or aspects thereof.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

I claim:
 1. A slider, comprising: a leading-edge surface; an air-bearingsurface (ABS) including a cavity with an opening oriented toward theleading-edge surface; and a back surface opposite the ABS, at least aportion of the back surface defining a plane, wherein an ABS function ofa cross-section of the slider taken perpendicular to the plane andthrough the cavity is a multi-valued function, and wherein no portion ofthe ABS function intersects the back surface.
 2. The slider recited inclaim 1, wherein the back surface is substantially flat and iscontinuous, and wherein the plane coincides with the back surface. 3.The slider recited in claim 2, wherein at least a portion of the ABS issubstantially parallel to the plane.
 4. The slider recited in claim 1,wherein: at least a portion of the leading-edge surface is substantiallyperpendicular to the plane, and the cross-section is substantiallyperpendicular to the at least a portion of the leading-edge surface. 5.The slider recited in claim 1, wherein: at least a portion of theleading-edge surface is substantially perpendicular to the plane, andthe cross-section is substantially parallel to the at least a portion ofthe leading-edge surface.
 6. The slider recited in claim 1, furthercomprising: a trailing-edge surface, wherein at least a portion of thetrailing-edge surface is substantially perpendicular to the plane, andwherein the cross-section is substantially perpendicular to the at leasta portion of the trailing-edge surface.
 7. The slider recited in claim1, further comprising: a trailing-edge surface, wherein at least aportion of the trailing-edge surface is substantially perpendicular tothe plane, and wherein the cross-section is substantially parallel tothe at least a portion of the trailing-edge surface.
 8. The sliderrecited in claim 1, wherein the cross-section is oriented along an axisin the plane, and wherein the multi-valued function has at least twodistinct values for at least one input value along the axis.
 9. Theslider recited in claim 1, wherein the cross-section is oriented alongan axis in the plane, and wherein the multi-valued function has exactlytwo distinct values for at least one input value along the axis.
 10. Theslider recited in claim 1, wherein the cross-section is oriented alongan axis in the plane, and wherein the multi-valued function has exactlythree distinct values for at least one input value along the axis. 11.The slider recited in claim 1, wherein the cross-section is orientedalong an axis in the plane, and wherein the multi-valued function hasexactly five distinct values for at least one input value along theaxis.
 12. The slider recited in claim 1, further comprising a head forreading from and writing to a disk.
 13. The slider recited in claim 1,wherein the opening is substantially parallel to the leading-edgesurface.
 14. The slider recited in claim 1, wherein the opening is at anangle to the leading-edge surface.
 15. The slider recited in claim 1,wherein the opening is rectangular.
 16. The slider recited in claim 1,wherein a shape of the cavity is uniform.
 17. The slider recited inclaim 1, wherein a shape of the cavity is irregular.
 18. The sliderrecited in claim 1, wherein the cavity is a first cavity, and theopening is a first opening, and wherein the ABS further comprises asecond cavity with a second opening oriented toward the leading-edgesurface.
 19. A magnetic storage system comprising a slider, the slidercomprising: a leading-edge surface; an air-bearing surface (ABS)including a cavity with an opening oriented toward the leading-edgesurface; and a back surface opposite the ABS, at least a portion of theback surface defining a plane, wherein an ABS function of across-section of the slider taken perpendicular to the plane and throughthe cavity is a multi-valued function, and wherein no portion of the ABSfunction intersects the back surface.
 20. The magnetic storage systemrecited in claim 19, wherein the slider further comprises a head forreading from and writing to a disk.